Electronic ignition system



arch 19, 1968 w. T. LEMEN 3,373,729

ELECTRONIC IGNITION SYSTEM Filed Dec. 10, 1965 2 Sheets-Sheet l ANPLIH ER nc SWITCH 3c COIL 354 I0 9 A INVENTOR.

WILLIAM T. LENEN ATTORNEY 2 Sheets-Sheet 2 W. T. LEMEN ELECTRONIC IGNITION SYSTEM In a March 19, 1968 Filed Dec.

Q L I x I.III|AIII| l l l l I l l I l I l I l l l I l I llll... I I v m$ n u m u u l n n w a T I h n \N v u n INVENTOR. WILLIAM T. LEMEN mgm ATTORNEY United States 3,373,729 ELECTRONIC IGNITION SYSTEM William T. Lemen, Frankfort, Ind., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed Dec. 10, 1965, Ser. No. 513,055 7 Claims. (Cl. 123-148) ABSTRACT OF THE DISCLOSURE A potential signal pulse generator having a rotor member comprised of two axially spaced flange portions, each having a plurality of permanent magnets mounted around the axis thereof in such a manner that each permanent magnet of one flange portion is in axial alignment with a corresponding permanent magnet of the other flange portion. A Hall Effect device is located between the flange portions and positioned in such a manner that the magnetic field produced by each permanent magnet pair is at right angles to the plane in which the input electrodes of the Hall Effect device lie.

The present invention relates to electronic ignition systems and, more specifically, to electronic ignition systems which include a potential signal pulse generator which produces a series of ignition synchronizing potential pulses, the amplitude of which is substantially independent of engine speed.

Recently, there has been increased activity in the development of electronic ignition systems for internal combustion engines, particularly in, but not necessarily limited to, the automotive field. To eliminate the disadvantages which are inherent in the conventional cam operated breaker point systems, magnetic type pulse generators which are arranged to produce a series of potential signal pulses in synchronism with the associated internal combustion engine have been developed for use with ignition systems of this type. As the amplitude of the pulses produced by magnetic pulse generators is dependent upon the rate of change of magnetic flux linking an electrical pick-up coil, the amplitude of the potential signal pulses produced by pulse generators of this type are dependent upon engine speed. A serious disadvantage of magnetic pulse generators is the low amplitude potential signal pulses produced thereby at low engine speeds, particularly during the cranking operation, which necessitates considerable additional circuitry to amplify these weak signals.

As electronic ignition systems are becoming increasingly popular, the requirement of an ignition system of this type which includes an ignition synchronizing potential signal pulse generator for producing a series of potential pulses in timed relationship with the associated engine and of an amplitude which is independent of the speed of the engine is apparent.

It is, therefore, an object of this invention to provide an improved electronic ignition system.

It is another object of this invention to provide an improved electronic ignition system which includes an igni-' tion synchronizing potential signal pulse generator of the type which produces a series of potential signal pulses, the amplitude of which is substantially independent of speed.

In accordance with this invention, an improved electronic ignition system for internal combustion engines is provided wherein the ignition synchronizing potential signal pulses are produced across the output electrodes of an electrical device having at least two input and two output electrodes and characterized by the ability, with a direct current flowing between the 'input electrodes, to produce a direct current potential between the output electrodes when positioned in a magnetic field which is at a right angle to the direction of current flow between the input electrodes, positioned to successively intersect a plurality of discrete magnetic fields which are at right angles to the plane in which the input electrodes of the device lie.

For a better understanding of the present invention, together with additional objects, advantages and features thereof, reference is made to the following description and accompanying drawings in which:

FIGURE 1 diagrammatically sets forth an internal combustion engine and an electronic ignition system,

FIGURE 2 is a top view of an acceptable rotor memher which may be used in the potential signal pulse generator of this invention,

FIGURE 3 is a sectional view of FIGURE 2 taken along line 33 and looking in the direction of the arrows, and

FIGURE 4 is a schematic diagram of an electronic ignition system.

Throughout the several figures of the drawings, like elements have been given like characters of reference.

Referring to FIGURE 1 of the drawings, an ignition system for an internal combustion engine 8 is diagrammatically set forth. Briefly, this ignition system includes an ignition coil 9 for producing the required high potentials, a switch 10, a conventional distributor 12 for directing the high potentials produced by coil 9 to the several spark plugs included in engine 8, schematically shown in FIGURE 1 as air gaps between opposed arrow heads generally shown at 13, and an ignition synchronizing potential signal pulse generator 14. Engine 8 and distributor 12 may be of conventional design well known in the art and, therefore, have been shown in block form. The circuitry included in the coil 9 and switch 10 blocks is schematically set forth in FIGURE 4 and details of the magnetic pulse generator 14 are shown in FIGURES 2, 3 and 4.

Switch 10 may be a semiconductor switching device such as transistor 15 of FIGURE 4 having two current carrying electrodes, collector electrode 16 and emitter electrode 17, and a control electrode, base electrode 18, and coil 9 may be a conventional ignition coil having a primary winding 19 and a secondary winding 20. The emitter-collector electrodes or current carrying electrodes of transistor 15 are connected in series with primary winding 19 of coil 9 across a source of direct current potential, which may be a conventional storage battery 21, through line 22 and current limiting resistor 24.

To produce the necessary ignition synchronizing potential signal pulses, a plurality of discrete magnetic fields and an electrical device, having at least two input and two output electrodes and characterized by the ability, with a direct current flowing between the input electrodes, to produce a direct current potential across the output electrodes when positioned in a magnetic field which is at a right angle to the direction of current flow between the input electrodes, are moved relative to each other in such a manner that the magnetic fields are successively intersected by this electrical device.

If an electrical conductor carrying a current is placed in a magnetic field which is at a right angle to the direction of current flow, an electrical potential difference may be observed across the electrical conductor in a direction which is at right angles to the direction of current flow and the magnetic field. The electrons flowing through the conductor are deflected in a direction which is at a right angle to 'both the current flow and the magnetic field. Because the electrons must travel within the confines of the conductor, an excess of electrons on one side of the conductor relative to the other causes an electric field to be established which just opposes the force produced by the magnetic field. This phenomenon is known as the Hall Effect and, by applying suitable contacts or output electrodes to the sides of the conductor, it is possible to detect and utilize this Hall voltage.

For any selected conductor dimension, applied voltage and magnetic flux density, the magnitude of the Hall voltage is proportional to the mobility factor of the conductor. The mobility factor is a mathematical expression of the ability of a conductor to permit the dispersion of electrons flowing therethrough in the presence of a magnetic field normal to the direction of current flow. Since this mobility factor is a property of the conductor, the Hall Effect can be enhanced by the proper choice of conductor material. Certain semiconductors possess very high values of mobility, and, therefore, are usually used for Hall Effect devices. One example of a semiconductor frequently used for Hall Effect devices is indium antimonide.

In usual practice, the small solid of indium antimonide or other acceptable semiconductor material is cut to the desired dimensions, length and width, and contacts are soldered to each of the four edges, two opposing contacts serving as input electrodes and the other two opposing contacts serving as output electrodes. The Hall voltage.

present across the output electrodes is proportional to both the input voltage and the intensity of the magnetic field in a direction normal to the plane of the contacts.

A Hall Effect device of this type may be employed as the electrical device in the ignition synchronizing signal pulse generator 14 of FIGURE 1 and is referenced by the numeral 26. Shaft 28 and a rotatable rotor member 30, pinned thereto, are rotated in timed relation with engine 8 in a manner well known in the automotive part. By producing a plurality of discrete magnetic fields in a direction parallel with and disposed around the axis of rotor member 30 and locating Hall Effect device 26 as shown in FIGURE 1, relative motion between the plurality of magnetic fields and Hall Effect device 26 may be produced by rotating rotor member 30' with shaft 28. Hall Effect device 26 may be secured to the housing 32 of pulse generator 14 by any suitable means well known in the art and should be positioned in such a manner that the plurality of discrete magnetic fields are at right angles to the plane in which the input electrodes of the Hall Effect device 26 lie.

The plurality of discrete magnetic fields may be produced by a plurality of permanent magnet pairs disposed around the axis of rotor member 30, each in axial alignment with and displaced from the corresponding magnet. Without intention or inference of a limitation thereto, rotor member 30 may include two circular, axially displaced flange portions 34 and 36, as shown in FIGURES 1 and 3. As engine 8 of FIGURE 1 is shown to have eight cylinders, mounted around the axis of flange portion 34 are eight circular permanent magnets 38, 39, 40, 41, 42, 43, 44 and 45, as shown in FIGURE 2. Mounted around the axis of flange portion 36 are eight other permanent magnets each in axial alignment with and axially displaced from a respective one of permanent magnets 38, 39, 40, 41, 42, 43, 44 and 45. In FIGURE 3, which is a section through FIGURE 2 taken along line 3-3 and looking in the direction of the arrows, two of these second mentioned magnets are shown and referenced by numerals 40a and 44a corresponding to the first mentioned permanent mag nets 40 and 44.

It is to be specifically understood that this method of producing discrete magnetic fields by locating a plurality of permanent magnet pairs about the periphery of rotor member 30 is not to be construed as limiting but as one method of providing for the necessary discrete magnetic fields and that, when used with engines having more or less than eight cylinders, correspondingly more or less discrete magnetic fields may be required.

As is shown in FIGURE 4, the input electrodes 46 and 47 of Hall Effect device 26 are connected across the positive and negative polarity terminals, respectively, of battery 21 through positive polarity potential line 49 and current limiting resistor 48 and negative polarity potential line 50.

The Hall voltage which appears across the output electrodes 51 and 52 of Hall Effect device 26 is applied to the control or base electrode 18 of transistor switch 15. Depending upon the application, the output electrode 52 of Hall Effect device 26 may be coupled to the control or base electrode 18 of transistor switch 15 or, should this Hall voltage be of such a low magnitude as to require amplification, the Hall voltage appearing across output terminals 51 and 52 may be applied to the base electrode 18 of transistor switch 15 through a coupling capacitor 23 and an amplifier 54, as shown in FIGURE 1. Amplifier 54 is shown in FIGURE 4 to be a conventional four stage amplifier.

Hall Effect device 26 is located between flange portions 34 and 36 of rotor member 30 and is positioned in such a manner that the magnetic fields between each of the permanent magnet pairs are successively intersected by Hall Effect device 26 as rotor member 30 is rotated in timed relationship with engine 8, as shown in FIGURE 1.

Hall Effect device 26 may be secured to housing 32 of the ignition signal pulse generator 14 by any suitable means well known in the art and is positioned between flange portions 34 and 36 in such a manner that the magnetic fields between each of the permanent magnet pairs is at right angles to the direction of current flow between input electrodes 46 and 47.

As rotor member 30 is rotated by engine 8, a Hall potential pulse appears across output electrodes 51 and 52 of Hall Effect device 26 as the magnetic field between each permanent magnet pair is intersected thereby. As rotor member 30 is driven in timed relationship with engine 8, these Hall potential pulses may be used as ignition synchronizing pulses.

Referring to FIGURE 4, the collector electrode 16 of type NPN transistor switch 15 is connected to the positive polarity terminal of battery 21 through current limiting resistor 24 and primary winding 19 of ignition coil 9 and the emitter electrode 17 thereof is connected to the negative polarity terminal of battery 21 through line 22. Therefore, the emitter-collector electrodes of this type NPN transistor are forward poled. The control or base electrode 18 of transistor 15 is connected through a resistor 55 to junction 56 between the collector electrode of type PNP transistor 60 and resistor 61. The opposite end of resistor 61 is connected to the negative polarity terminal of battery 21.

In normal operation, transistor 65 is normally conducting, transistors and are normally nonconducting and transistor 60 is normally conducting. With transistor 60 conducting, the potential at junction 56 is of a positive relative to line 50 and of a magnitude substantially equal to the supply potential of battery 21. As this is the proper potential relationship for base-emitter current fiow through a type NPN transistor, switching transistor device 15 is normally conducting, and, therefore, completes an energizing circuit for primary Winding 19 of ignition coil 9.

Upon the appearance of a Hall voltage across the baseemitter electrodes of type NPN transistor 65 which is of a negative polarity at output terminal 52, transistor 65 is triggered nonconductive and the potential at junction 66 goes positive in respect to line 50. This positive polarity potential is applied to the base electrode of type NPN transistor 70 and is of the correct polarity relationship to produce base-emitter current flow through a type NPN transistor, consequently, this device goes conductive. With transistor 70 conducting, the potential at junction 71 goes positive in respect to line 49. This pulse is integrated by the resistor-capacitor network including resistors 72 and 73 and capacitor 74. The trailing edge of this pulse, being negative going, triggers type PNP transistor 75 to conduction. With transistor 75 conducting, the potential at junction 76 goes positive in respect to line 50. This positive potential applied to the base electrode of type PNP transistor 60 is of the incorrect polarity relationship to produce base-emitter current fiow through a type PNP transistor, consequently, transistor 60 is extinguished. As transistor 60 extinguishes, the potential at junction 56 goes negative in respect to line 49. As this negative potential, applied to the base electrode 18 of switching transistor is of the incorrect polarity relationship to produce base-emitter current flow through a type NPN transistor, this device is triggered nonconductive,

As switching transistor 15 goes nonconducting, the energizing circuit for primary coil 19 of ignition coil 9 is interrupted and the resulting collapsing magnetic field produces a high potential across output terminal 80 thereof and point of reference or ground potential 5. This high potential is conducted to the rotor of distributor 12 of FIGURE 1 through line 81, which directs it to the proper spark plug of engine 8.

As transistor 75 is turned off after a very short period of time by the integrated pulse appearing across capacitor 74, this device quickly goes nonconductive and the remainder of the circuit'returns to its original condition, with transistor switching device 15 conducting, to complete an energizing circuit for primary winding 19 of ignition coil 9 as previously described.

As rotor member 30 is rotated by engine 8 through shaft 28, successive magnetic fields are intersected by Hall Effect device 26, each intersection producing a Hall voltage potential pulse across the output terminals 51 and 52 thereof. This Hall Effect voltage is applied to the base or control electrode 18 of transistor 15 in a manner just described. As each of these potential pulses trigger switching transistor 15 to nonconduction to interrupt the energizing circuit for primary winding 19 of ignition coil 18, these potential pulses may be used as the ignition synchronizing pulses for engine 8.

While a preferred embodiment of the present invention has been shown and described, it will be obvious to those skilled in the art that various modifications and substitutions may be made without departing from the spirit of the invention which is to be limited only within the scope of the appended claims.

What is claimed is as follows:

1. An ignition system for internal combustion engines comprising, a source of direct current potential, an ignition coil having primary and secondary windings, a semiconductor switching device having at least two current carrying electrodes and a control electrode, means for connecting said current carrying electrodes in series with said primary winding across said direct current potential source, an ignition synchronizing signal pulse generator including a rotor member adapted to be rotated in timed relationship with said engine, means for producing a plurality of discrete magnetic fields in a direction parallel with and disposed around the axis of said rotor member, a Hall Effect device having input and output electrodes, means for connecting said input electrodes across said source of direct current potential, means for locating said Hall Effect device relative to said rotor member in such a manner that, as said rotor member rotates, said magnetic fields are successively intersected by said Hall Effect device and for positioning said Hall Effect device in such a manner that said magnetic fields are at right angles to the direction of current flow between said input electrodes and means for applying the signals appearing across said output electrodes to the said control electrode of said semi-conductor switching device.

2. A potential signal pulse generator comprising, means for producing a plurality of discrete magnetic fields, an electrical device having at least two input and two output electrodes and characterized by the ability, with a direct current flowing between said input electrodes, to produce a direct current potential across said output electrodes when positioned in a magnetic field which is at a right angle to the direction of current flow between said input electrodes, means for producing relative motion between said magnetic fields and said electrical device in such a manner that said magnetic fields are successively intersected by said electrical device and means for positioning said electrical device in such a manner that said magnetic fields are at right angles to the plane in which said input electrodes lie.

3. The potential signal pulse generator described in claim 2 wherein said electrical device is a Hall Effect device.

4. A potential signal pulse generator comprising, a

magnets mounted around the axis of said rotor member and a second plurality of permanent magnets mounted around the axis of said rotor member, each axially displaced from and in axial alignment with one of said first plurality of permanent magnets, for producing a plurality of discrete magnetic fields in a direction parallel with and disposed around the axis of said rotor member, a Hall Effect device having input and output electrodes and means for locating said Hall Effect device relative to said rotor member in such a manner that said magnetic fields may be successively intersected by said Hall Effect device and for positioning said Hall Effect device in such a manner that said magnetic fields are at right angles to the plane in which said input electrodes lie.

5. The potential signal pulse generator described in claim 4 wherein said rotor member has two axially displaced flange portions and said means for producing a plurality of discrete magnetic fields comprises, a first plurality of permanent magnets mounted around the axis of one of said flange portions and a second plurality of permanent magnets mounted around the axis of the other one of said flange portions, each in axial alignment with one of said first plurality of permanent magnets.

6. A potential signal pulse generator comprising, a rotatable rotor member, a first and a second plurality of permanent magnets mounted around the axis of said rotor member in such a manner that each one of said permanent magnets of either said plurality of permanent magnets is axially displaced from and in axial alignment with one of said permanent magnets of the other of said plurality of permanent magnets for producing a plurality of discrete magnetic fields in a direction parallel with and disposed around the axis of said rotor member, a source of direct current potential, a Hall Effect device having input and output electrodes, means for connecting said input electrodes across said source of direct current potential and means for locating said Hall Effect device relative to said rotor member in such a manner that, as said rotor member rotates, said magnetic fields are successively intersected by said Hall Effect device and for positioning said Hall Effect device in such a manner that said magnetic fields are at right angles to the direction of current fiow between said input electrodes.

7. The potential signal pulse generator described in claim 6 wherein said rotor member has two axially displaced fiange portions each having a plurality of permanent magnets mounted around the axis thereof in such a manner that each said permanent magnet mounted around the axis of one of said flange portions in an axial alignment with one of said permanent magnets mounted around the axis of the other one of said flange portions.

References Cited UNITED STATES PATENTS 3,152,281 10/1964 Robbins 123-148 3,297,009 1/1967 Sasaki et a1. 123148 LAURENCE M. GOODRIDGE, Primary Examiner. 

